1. Field of the Invention
The present invention relates to a method for manufacturing nanophase TiC-based composite powders by means of metallothermic reduction, and more particularly to a method for economically manufacturing high quality TiC powder, TiCN powder or ultrafine nanophase TiC+Ni (Co, Al) and TiCN+Ni (Co, Al) composite powders by means of metallothermic reduction.
2. Description of the Related Art
In general, titanium carbide (TiC) and titanium carbo-nitride (TiCN) powders are currently used as additives for improving high-temperature hardness and wear-resistance of WC/Co hard metal tools. In addition, these powders are widely used as starting powders for manufacturing cermet tools, rolls and molds by forming composites with metal powders, e.g., Ni powder.
As traditional processes for manufacturing TiC and TiCN powders, reduction/carburization of titanium dioxide (TiO2), direct carburization of Ti and TiH2, self heated sintering processes, sol-gel processes and mechanical alloying (MA) processes, etc., have been developed.
These processes have difficulty in their commercial uses due to the following problems.
That is, the reduction/carburization of titanium dioxide requires a very high reaction temperature of as high as 2000° C., which is economically disadvantageous. Since the direct carburization using Ti and TiH2 and self heated sintering processes use an expensive starting material (high purity sponge titanium powder), there is a problem of high manufacturing costs. The sol-gel process and the mechanical alloying (MA) process have problems of difficult stoichiometric manufacturing of TiC and TiCN powders and serious impurity incorporation during manufacture of TiC and TiCN powders, etc.
In addition, according to the above-mentioned processes, since finally manufactured powders are often obtained in the form of oxides such as TiCxOy or TiCxNyOz, there is a difficulty in the manufacture of desired high quality powders. Furthermore, the processes require a separate grinding step, such as re-milling, to obtain a desired particle size, owing to severe sintering of TiC by high reaction temperature.